Pliosaurids are a large family of short-necked plesiosaurs within the superfamily Pliosauroidea. They have a reduced number of neck vertebrae and are often large skulls. In some genera the skull may reach up to 3 meters in length and make up about a quarter of the total length of the animal. The Pliosauridae is usually placed in a sister relationship with a second group of pliosaurs, the Rhomaleosauridae.

Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany (from Martill and Naish, 2000).

The family Brachaucheninae has been proposed for pliosaurs which have very short necks and lack typical nutritive foramina on the vertebrae. This group includes Brachauchenius and Kronosaurus.

Pliosaurid genera


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Attenborosaurus is an unusual plesiosaur because it combines a long neck with a relatively large head. It is classified as a pliosaur in some classifications, but some phylogenies place it in a more basal position. The genus was introduced for ‘Plesiosaurus’ conybeari, a species originally described by Sollas (1881). Bob Bakker coined the new genus …


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Hauffiosaurus is a basal pliosaurid known from the Lower Jurassic (Toarcian) of the UK and Germany. Hauffiosaurus is a medium to large sized plesiosaur (H. zanoni = 3.4 m, H. tomistomimus, 4.23 m, H. longirostris = 4.83 m) (Smith and Lomax, 2019), with a relatively long neck for a pliosaur, and an elongate narrow snout. …


Due to its large size and ferocious appearance, Kronosaurus is one of the most famous plesiosaurs. The iconic skeleton referred to Kronosaurus on display in the Museum of Comparative Zoology in Harvard is nicknamed ‘plasterosaurus’ because so much of it is reconstructed in plaster. About a third of the skeleton is plaster and there are …


Liopleurodon is a pliosaur that hardly needs introduction since appearing as the villain in the BBC’s ‘Walking with Dinosaurs’ TV series. This led to popular misconceptions about the size of Liopleurodon, which is known to have reached adult sizes in the region of seven metres long, nowhere near the gargantuan 25m estimate proposed by the …


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Pachycostasaurus is approximately 3.1 meters long. Its rib cage and vertebrae exhibit thickened bone (Cruickshank et al. 1996) a condition termed pachyostosis. This heavy ossification is unusual in plesiosaurs (another exception may include Kronosaurus), although it is common in basal sauropterygians, especially pachypleurosaurs. Pachycostasaurus probably used the extra ballast provided by its heavy bones to …


Peloneustes is one of several pliosaur genera from the Oxford Clay Formation in the UK. It is one of the better known pliosaurs from this horizon, represented by 12 nearly complete skulls and several skeletons. It is also the most abundant pliosaur from the Peterborough Member of the Oxford Clay Formation (Ketchum and Benson, 2011). …


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Simolestes has variously been allied with the Pliosauridae and the Rhomaleosauridae. The most noticeable difference between Simolestes and the other pliosaur taxa from the Oxford Clay (Liopleurodon, Peloneustes, Pachycostasaurus), is its much shorter snout and mandibular symphysis, a character is shares with the Rhomaleosauridae. However, this is probably a convergent character. Older descriptions of this …


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Several pliosaurid genera are considered nomina dubia or are regarded as junior synonyms of other genera. The following names are therefore invalid:

  • ‘Stretosaurus’ = Liopleurodon?